Buzz Aldrin has tweeted an ominous warning on Twitter this week, claiming that “we are all in danger. It is evil itself,” accompanied by a picture of a pyramid at the South Pole.

The tweet comes days after the U.S. astronaut was mysteriously taken ill in Antarctica.

The emergency request for an “ailing visitor” was made by The Antarctic Company, a South African tourism company, according to the NSF. The International Association of Antarctic Tour Operators confirmed Aldrin’s evacuation, saying he was “stable” when he was taken from the South Pole to McMurdo base in Antarctica.

Since retiring from NASA and the U.S. Air Force, Col. Aldrin calls himself a Global Statesman for Space and has remained a tireless advocate for human space exploration.

Legendary astronaut Buzz Aldrin has left the New Zealand hospital he was evacuated to after falling ill during a trip to the South Pole.

Why did Buzz Aldrin warn that we are all in danger? Why did he call it “Evil itself?”